有没有大佬来看看我这个蒟蒻的代码

#include <bits/stdc++.h>
using namespace std;
int main()
{
	int year,ryear=0,pyear=0,sumday,shift;
	cin >> year;
	if(year==1913)
	{
		cout << 11;
		return 0;
	}
	for(register int i=1914;i<year;i++)
	{
		if((i%4==0&&i%100!=0)||i%400==0)
			ryear++;
		else
			pyear++;
	}
	sumday+=234+ryear*366+pyear*365;
	if((year%4==0&&year%100!=0)||year%400==0)
		sumday+=121;
	else
		sumday+=120;
	shift=sumday%7;
	switch(shift)
	{
		case 0:cout << 14 << endl;break;
		case 1:cout << 13 << endl;break;
		case 2:cout << 12 << endl;break;
		case 3:cout << 11 << endl;break;
		case 4:cout << 10 << endl;break;
		case 5:cout << 9 << endl;break;
		case 6:cout << 8 << endl;break;
	}
 	return 0;
}

我手打样例全对，结果一测死活不AC